Controller/drivers used for driving display panels are often comprised of display memories for storing image data. Such controller/drivers receive image data representing images to be display on display panels from image processors, and temporally store the received image data into display memories. The controller/drivers are responsive to the image data stored in the display memories for driving data lines of display panels.
In order to achieve increased grayscale capacity and improved smoothness of moving pictures, increased image data are required to be provided for controller/drives. Increase in the number of the graylevels of image data requires the number of data bits of image data for each pixel, and this leads to the increase in the amount of image data. Additionally, improvement of smoothness of moving pictures requires numbers of frames per unit of time, and this also leads to increase in the amount of image data.
Nevertheless, the increase in the amount of image data is undesirable because it results in the power consumption of controller/drivers. Controller/drives consume power when receiving image data, and therefore increase in image data increases the power consumption. The increased power consumption is undesirable especially for portable electronic devices, including cell phones and PDAs (personal data assistants).
Japanese Open Laid Patent Application No. P2002-182627A discloses a controller/driver for reducing power consumption. The disclosed controller/driver includes a latch circuit which latches image data and a display memory which does not include any sense amplifiers. The controller/driver writes a plurality of data bits into the display memory at the same time, and thereby reduces the number of times of activation of word lines within the display memory, that is the number of access times to the display memory. This effectively reduces power consumption of the controller/driver.
As mentioned before, reduction in power consumption is critically important for portable electronic devices, including cell phones and PDAs; therefore, it would be desirable if controller/drivers achieve further reduction in power consumption. There is a need for controller/drivers that further reduces power consumption.